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Monitoring Unregulated Drinking Water Contaminants

First Unregulated Contaminant Monitoring Rule

You will need Adobe Reader to view some of the files on this page. See EPA’s About PDF page to learn more.The The 1996 Safe Drinking Water Act (SDWA) amendments require that once every five years EPA issue a new list of no more than 30 unregulated contaminants to be monitored by public water systems (PWSs). The first Unregulated Contaminant Monitoring Rule (UCMR 1) was published on September 17, 1999, and through supplemental actions on March 2, 2000, and January 11, 2001.

UCMR 1 required monitoring for 26 contaminants between 2001 and 2003 using analytical methods developed by EPA, consensus organizations, or both. This monitoring provides a basis for future regulatory actions to protect public health.

On this page:

UCMR 1 contaminants

Assessment monitoring (List 1 contaminants)

All PWSs serving more than 10,000 people and 800 representative PWSs serving 10,000 or fewer people were required to monitor for 12 List 1 contaminants during a 12-month period from January 2001 through December 2003.  The 12 contaminants were:

  • 2,4-dinitrotoluene
  • 2,6-dinitrotoluene
  • Acetochlor
  • DCPA mono-acid degradate
  • DCPA di-acid degradate
  • 4,4'-DDE
  • EPTC
  • Molinate
  • MTBE
  • Nitrobenzene
  • Perchlorate
  • Terbacil

Fact sheets for assessment monitoring of List 1 contaminants:

Screening survey (List 2 contaminants)

All PWSs serving more than 100,000 people, 320 representative PWSs serving 10,001 to 100,000 people, and 480 representative PWSs serving 10,000 or fewer people were required to monitor for 13 List 2 contaminants during a 12-month period from January 2001 through December 2003.  The 13 contaminants were:

  • 1,2-diphenylhydrazine
  • 2-methyl-phenol
  • 2,4-dichlorophenol
  • 2,4-dinitrophenol
  • 2,4,6-trichlorophenol
  • Diazinon
  • Disulfoton
  • Diuron
  • Fonofos
  • Linuron
  • Nitrobenzene
  • Prometon
  • Terbufos
  • Aeromonas

Fact sheets for the screening survey of List 2 contaminants:

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Federal Register Notices

On October 29, 2002, EPA published a final rule to approve EPA Method 1605 to monitor Aeromonas. The rule also specified that laboratories wishing to be approved for this method must participate in an Aeromonas proficiency testing (PT) program conducted by EPA.

On March 12, 2002, EPA published a rule to establish the electronic reporting date for monitoring results.

On March 7, 2002, EPA published a proposed rule to approve EPA Method 1605 to monitor Aeromonas.

On September 4, 2001, EPA published a direct final rule to amend the List 2 requirements and delay the requirements for the electronic reporting of monitoring results.

On January 11, 2001, EPA published analytical methods for several screening survey List 2 contaminants and described the required monitoring for those contaminants. In this notice, EPA also modified the UCMR to improve the implementation of monitoring for both List 1 and List 2 contaminants.

On March 2, 2000, EPA published a rule specifying the approved analytical methods for perchlorate and acetochlor. EPA included a notice about a laboratory approval process for laboratories interested in participating in perchlorate monitoring.

On January 8, 1999, EPA published a rule suspending unregulated contaminant monitoring for small public water systems.

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